Apparatus and method for optical encoding and cursor control trackball

Abstract

An apparatus for optical encoding. An electrical input circuitry is provided for providing a pulsed electrical input signal. A light source circuitry is connected to the pulsed electrical input circuitry for utilizing the pulsed electrical input signal to produce pulses of light. Light collecting and electrical conducting circuitry is provided and synchronized with the light source circuitry. The light collecting and electrical conducting means is positioned in relation to the light source circuitry for receiving and being responsive to light produced by the pulsed light source circuitry. An electrical output signal is produced, indicating such a response. Positionable light interrupting circuitry is provided for opening and closing the optical path of light being transmitted from the light source circuitry to the light collecting and electrical conducting circuitry. The opening and closing affects the electrical output signal, the resulting pulsed electrical output signal for use in encoding. The apparatus results in minimized power consumption as a result of the pulsed synchronization of the light source circuitry and the light collecting and electrical conducting circuitry. The present invention is particularly adaptable for use with cursor control devices for computer controlled display systems.

What is claimed and desired to be secured by Letters Patent of the United States is: 
     
       1. An apparatus for optical encoding with respect to a first axis and a second axis, comprising: (a) a first axis assembly that includes: (1) first axis electrical input means for providing a first axis pulsed electrical signal;   (2) a first light emitting device having a first path a light emission and having a first terminal coupled to the first axis electrical input means;   (3) a second light emitting device coupled in series with the first light emitting device, wherein the second light emitting device has a second path of light emission and has a first terminal coupled to a second terminal of the first light emitting device;   (4) a first photodetector residing in the first path of light emission and having a first terminal coupled to the first axis electrical input means such that when said first light emitting device goes to zero volts said first photodetector goes to zero volts in response to the first axis pulsed electrical signal;   (5) a second photodetector residing in the second path of light emission and having a first terminal coupled to the first axis electrical input means such that when said second light emitting device goes to zero volts said second photodetector goes to zero volts in response to the first axis pulsed electrical signal;   (6) first axis positionable light blocking means for blocking and unblocking the first path of light emission and for blocking and unblocking the second path of light emission;     (b) a second axis assembly that includes: (1) second axis electrical input means for providing a second axis pulsed electrical signal, wherein the second axis pulsed electrical signal is substantially 180° out of phase with the first axis pulsed electrical signal;   (2) a third light emitting device having a third path of light emission and having a first terminal coupled to the second axis electrical input means;   (3) a fourth light emitting device coupled in series with the third light emitting device, wherein the fourth light emitting device has a fourth path of light emission and has a first terminal coupled to a second terminal of the third light emitting device;     (4) a third photodetector residing in the third path of light emission and having a first terminal coupled to the second axis electrical input means such that when said third light emitting device goes to zero volts said third photodetector goes to zero volts in response to the second axis pulsed electrical signal; (5) a fourth photodetector residing in the fourth path of light emission and having a first terminal coupled to the second axis electrical input means such that when said fourth light emitting device goes to zero volts said fourth photodetector goes to zero volts in response to the second axis pulsed electrical signal;   (6) second axis positionable light blocking means for blocking and unblocking the third path of light emission and for blocking and unblocking the fourth path of light emission;     (b) encoding means having (1) a first input coupled to a second terminal of the first photodetector and a second terminal of the third photodetector and   (2) a second input coupled to a second terminal of the second photodetector and a second terminal of the fourth photodetector.     
     
     
       2. The apparatus of claim 1 for optical encoding, wherein the first and second axes are orthogonal. 
     
     
       3. The apparatus of claim 1 for optical encoding, wherein the first axis is an X axis and the second axis is a Y axis. 
     
     
       4. The apparatus of claim 1 for optical encoding, wherein the light emitting device is a light emitting diode, and wherein the photodetector is a phototransistor. 
     
     
       5. A trackball for optical encoding with respect to a first axis and a second axis, comprising: (a) a first axis assembly that includes: (1) first axis electrical input means for providing a first axis pulsed electrical signal;   (2) a first light emitting device having a first path of light emission and having a first terminal coupled to the first axis electrical input means;   (3) a second light emitting device coupled in series with the first light emitting device, wherein the second light emitting device has a second path of light emission and has a first terminal coupled to a second terminal of the first light emitting device;   (4) a first photodetector residing in the first path of light emission and having a first terminal coupled to the first axis electrical input means such that when said first light emitting device goes to zero volts said first photodetector goes to zero volts in response to the first axis pulsed electrical signal;   (5) a second photodetector residing in the second path of light emission and having a first terminal coupled to the first axis electrical input means such that when said second light emitting device goes to zero volts said second photodetector goes to zero volts in response to the first axis pulsed electrical signal;   (6) first axis positionable light blocking means for blocking and unblocking the first path of light emission and for blocking and unblocking the second path of light emission;     (b) a second axis assembly that includes: (1) second axis electrical input means for providing a second axis pulsed electrical signal, wherein the second axis pulsed electrical signal is substantially 180° out of phase with the first axis pulsed electrical signal;   (2) a third light emitting device having a third path of light emission and having a first terminal coupled to the second axis electrical input means;   (3) a fourth light emitting device coupled in series with the third light emitting device, wherein the fourth light emitting device has a fourth path of light emission and has a first terminal coupled to a second terminal of the third light emitting device;     (4) a third photodetector residing in the third path of light emission and having a first terminal coupled to the second axis electrical input means such that when said third light emitting device goes to zero volts said third photodetector goes to zero volts in response to the second axis pulsed electrical signal; (5) a fourth photodetector residing in the fourth path of light emission and having a first terminal coupled to the second axis electrical input means such that when said fourth light emitting device goes to zero volts said fourth photodetector goes to zero volts in response to the second axis pulsed electrical signal;   (6) second axis positionable light blocking means for blocking and unblocking the third path of light emission and for blocking and unblocking the fourth path of light emission;     (c) encoding means having (1) a first input coupled to a second terminal of the first photodetector and a second terminal of the third photodetector and   (2) a second input coupled to a second terminal of the second photodetector and a second terminal of the fourth photodetector.     
     
     
       6. The trackball of claim 5 for optical encoding, wherein the first and second axes are orthogonal. 
     
     
       7. The trackball of claim 5 for optical encoding, wherein the first axis is an X axis and the second axis is a Y axis. 
     
     
       8. The trackball of claim 5 for optical encoding, wherein the light emitting device is a light emitting diode, and wherein the photodetector is a phototransistor.